Image transmission system



July 14, '1959 D. D. WILLARD IMAGE TRANSMISSION SYSTEM Filed Aug.- 15, 1955 L H F S A G D E L i F S A G 2 INVENTOR.

DENNIS p. WILLARD ATTORNEY States Patent Patented July 14, 1959 fitice IMAGE TRANSMISSION SYSTEM Application August 15, 1955, Serial No. 528,231

8 Claims. (Cl. 315-153) This invention relates to image transmission systems, and more particularly to apparatus for converting an optical image into a plurality of electrical potentials, and after transmission, for converting these potentials into an optical image.

-A principal object of the present invention is to provide an improved image transmission system.

Another object is to provide an image transmission system utilizing plural ionization chambers.

A further object is to provide an image transmission system in which a first ionization chamber converts an optical image into a plurality of electrical potentials and a second ionization chamber utilizes these potentials to reproduce the original optical image.

In accordance with the present invention, there is provided an image transmission apparatus comprising first and second ionization chambers, means for utilizing the first chamber to convert an optical image into a plurality of electrical potentials, means for transmitting these potentials to the second chamber, and means for utilizing the second chamber to convert the potentials into an optical image. In a preferred embodiment of the invention, the ionization chambers are filled with an ionizable medium such as, for example, a polyatomic gas or the vapor of a compound having a relatively high molecular weight.

It is well known, as disclosed in Lion Patent 2,692,948, issued October 26, 1954, that discharges from needlepoint electrodes or probes, such as those utilized in the system of the present invention, travel in straight lines and remain very sharply defined. Advantage is taken of this fact to achieve the production of a faithfully reproduced image at the receiving portion of the system.

Other objects and features of the present invention will be pointed out in the following description and claims and illustrated in the accompanying drawing, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawing, in which like reference numerals designate like components:

Fig. l is a diagrammatic view, partly in section, of an image transmission system in accordance with the invention; and

Fig. 2 is a sectional view taken on line 22 of Fig. 1.

Referring to the drawing, the system comprises a transmitting unit 10 and a receiving unit 11, each having a cylindrical shell member respectively designated 12 and 13. These shell members are made of any suitable insulating material.

Considering first transmitting member 10, it comprises a transparent conductive member 14, a layer of photoemissive material 15 on one surface of element 14, and a layer 16 of material adapted for blocking ultra-violet radiation superimposed on layer 15. Elements 14, 15 and 16 effectively provide a closure for one end of shell member 12. The other end of shell member 12 is closed by an insulating member 17 through which protrude a mosaic of needlepoint electrodes or probes collectively designated by reference numeral 18. The resultant chamber 19, formed by shell member 10 and its respec tive front and back closures, is filled with an ionizable medium, as for example a polyatomic gas or the vapor of a compound having a relatively high molecular weight.

Receiving unit 11 has one end of its shell member 13 closed by an insulating member 20 through which pro trude a plurality of needlepoint electrodes or probes collectively designated by reference numeral 21. The oppo site end of shell member 13 is closed by an element 22 comprising a transparent conductive material. The inner surface of element 22 is covered first with a relatively thin layer 23 of phosphor or electro-lumine'scent material, upon which may be superimposed a thin layer 24 of photo-emissivev material. The chamber 25 formed by shell member 13 and its respective closures is filled with an ionizable medium, as for example a polyatomic gas or the vapor of a compound having a relatively high molecular weight.

Conductive element 14 of transmitting unit 10 is connected through a suitable direct-current potential source or battery 26 to conductive element 22 of receiving unit 11. Probes 18 of transmitting unit 10, are connected by suitable wires 27 to the correspondingly located probes 21 in receiving unit 11. Each of wires 27 is connected through an individual resistor to lead 28 between battery 26 and conductive element 22, these resistors having equal values and being collectively designated by reference numeral 29.

The ohmic values of resistors 29 and the voltage of the source 26 are dependent on a number of factors, such as, for example, the spacing of the probes from the opposite wall of the chamber, the type and pressure of gas in the chambers, and so forth. The voltage of source 26 may be of the order of several hundred to several thousand volts, and correspondingly, the values of resistors 29 may be of the order of 1 to 20 megohrns.

In operation, it is first assumed that the ambient light at receiving unit 11 is sufiicient to ionize the gas molecules in chamber 25, so that the receiving unit is recep. tive to any potential developed between probes 21 and conductive element 22. The achievement of this condition of readiness is obtained by the provision of photoemissive layer 24.

When a light image is projected onto transparent conductive element 14 of transmitting unit 10, localized dischargestake place between this element and those probes 18 which are directly behind the lighted portion of element 14. This is due to the presence of photoemissive layer 15. Layer 16 serves to prevent undesired regeneration due to the individual discharges in the gas, by effectively shielding layer 15 from these discharges take place between this element and those resistance path between a lighted portion of conductive element 14 and the corresponding probe 18 causes a large voltage drop across the particular resistor 29 associated With this probe. This potential is applied between corresponding probe 21 and transparent element 22 in receiving unit 11. The resulting ionization of the gas in chamber 25 causes phosphor layer 23 to be illuminated in the area opposite the particular probe involved. Taking the system as a Whole, therefore, a light image is produced by receiving unit 11 which corresponds with that originally projected onto transparent element 14 of transmitting unit 10.

It will be understood that, for purposes of simplicity, the drawing does not show as many probes and connecting wires as would normally be used. As will be readily apparent to those skilled in the art, the device could be made sufiiiciently small to serve as an optical plug wire which could be utilized in character sensing, in

optical computing equipment, or for the direct transmission of optically stored information.

In addition to converting to visual light inthe manner together with an alternating-current generator as the potential source instead of battery 26, or by the combination of both of these conversion arrangements, since certain electroluminescent materials also react to ultraviolet radiations. These and other modifications may be made without departing from the scope of the present invention.

By adding voltage taps to each of Wires 27, the system of the present invention may readily be utilized for printing by ferrography, electrostatic or facsimile means.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the in vention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. Image transmission apparatus comprising: first and second ionization chambers, means including a first transparent conductive layer, a photo-emissive layer, and a first group of plural probes for utilizing ionization in said first chamber to convert an optical image into a plu rality of electrical potentials, means including a second ductive layer for utilizing ionization in said second chamber to convert said potentials into an optical image; conductive means between corresponding probes of said first and second groups, and a potential source connected between said first and second conductive layers.

5. Image transmission apparatus comprising: first and second ionization chambers; means including a first congroup of plural probes and a second transparent conductive layer for utilizing ionization in said second chamber to convert said potentials into an optical image, con:

ductive means between corresponding probes of said first and second groups, and a potential source connected between said first and second conductive layers.

2. Image transmission apparatus comprising: first and second ionization chambers, means including a first conductive layer, a photo-emissive layer, and a first group of plural probes for utilizing ionization in said first chamber to convert an optical image into a plurality of electrical potentials, means including a second group of plural probes and a second conductive layer for utilizing ionization in said second chamber to convert said potentials into an optical image, conductive means between corresponding probes of said first and second groups, individual resistive elements connected between said conductive means and said second conductive layer, and a potential source connected between said first and second conductive layers.

3. Image transmission apparatus comprising: first and second ionization chambers; means including a first conductive layer, a photo-emissive layer and a first group of plural probes for utilizing ionization in said first chamber to convert an optical image into a plurality of electrical potentials; means including a second group of plural probes and a second conductive layer for utilizing ionization in said second chamber to convert said potentials into an optical image; conductive means between corresponding probes of said first and second groups; and a potential source connected between said first and second conductive layers.

4. Image transmission apparatus comprising: first and second ionization chambers; means including a first conductive layer, a photo-emissive layer, and a first group of plural probes for utilizing ionization in said first chamber to convert an optical image into a plurality of electrical potentials; means including a second group of plural probes, a luminescent layer and a second conductive layer, a photo-emissive layer and a first group of plural probes for utilizing ionization in said first charm ber to convert an optical image into a plurality of electrical potentials; means including a second group of plural probes, a luminescent layer and a second conductive layer for utilizing ionization in said second chamber to convert said potentials into an optical image; conductive means between corresponding probes of said first and second groups; and a potential source connected between said first and second conductive layers.

6. Image transmission apparatus comprising: first and second ionization chambers; means including a first coni ductive layer, a photo-emissive layer and a first group of plural probes for utilizing ionization in said first chamber to convert an optical image into a plurality of electrical potentials; means including a second group of plural probes, a luminescent layer and a second conductive layer for utilizing ionization in said second chamber to convert i said potentials into an optical image; conductive means between corresponding probes of said first and second groups; individual resistive elements connected between i said conductive means and said second conductive layer; and a potential source connected between said first and second conductive layers.

7. Image transmission apparatus comprising: first and second ionization chambers, each of said chambers con taining an ionizable medium; means including a first transparent conductive layer, a photo-emissive layer, and a first group of plural probes for utilizing ionization of said medium in said first chamber to convert an optical image 1 into a plurality of electrical potentials; means includlng a second group of plural probes and a second transparent conductive layer for utilizing ionization of said medium in said second chamber to convert said potentials into an optical image; conductive means between corresponding probes of said first and second groups; and a potential source connected between said first and second conduc tive layers.

8. Image transmission apparatus comprising: first and second ionization chambers, each of said chambers containing an ionizable medium; means including a first conductive layer, a photo-emissive layer and a first group of plural probes for utilizing ionization of said medium in said first chamber to convert an optical image into a plurality of electrical potentials; means including a second group of plural probes, a luminescent layer and a second conductive layer for utilizing ionization of said medium in said second chamber to convert said potentials into an 1 optical image; conductive means between corresponding probes of said first and second groups; individual resistive elements connected between said conductive means and said second conductive layer; and a potential source.

connected between said first and second conductive lflYIS.,

References Cited in the file of this patent UNITED STATES PATENTS 

